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Re: Newbie

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  • caljer
    Thx Steve. Exactly, window dressing! I try to run the small addition program from the manual, but as I said in my first post, whatever I deposit in a memory
    Message 1 of 6 , Feb 29, 2004
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      Thx Steve. Exactly, window dressing!
      I try to run the small addition program from the manual, but as I
      said in my first post, whatever I deposit in a memory location has
      bit D4 ON. (i.e. if I Deposit 00 000 000, I get 00 010 000 when I
      Examine) So I have to check the wiring. I already cleaned the edge
      connectors. The wiring is a little more involved...
      Any other idea for this kind of behavior?

      I posted a higher def pic of the wire wrap board. The board has an
      UART TMS 6011 and two 555. I believe that it was wired as a dual
      function tape recorder interface and serial interface. But it's a
      guess based on connectors as well as schematics in the binder.


      Jerome


      --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@y...>
      wrote:
      > Thanks for posting the pictures. Your computer looks pretty
      clean.
      > Was the music store using it for anything other than a blinky-light
      > window dressing? Have you been able to run any programs on it
      yet?
      > What's the function of the blue wire wrap board in the pictures
      > labeled "MyAltair8800_10" and "MyAltair8800_11"?
      >
      > Steve
      > ==========================
      >
      > --- In altaircomputerclub@yahoogroups.com, "caljer" <caljer@y...>
      > wrote:
      > > Hello,
      > >
      > > I'm the proud owner of a MITS Altair 8800 serial# 222027K
      acquired
      > > sometime in 2003. I got it from a music store in Mountain View,
      CA.
      > > The computer was on display in the store window among various
      music
      > > intruments and with its LEDs blinking. I had to look several
      times
      > to
      > > make sure it was not some kind of fake computer. Kind of a chock,
      > > being a member of the Computer History Museum in Mountain View.
      > > <http://www.computerhistory.com>. I can now brag about it ;-)
      > >
      > > Anyway I have it now and it was sitting in my garage until today.
      I
      > > tested it (looks like one bit is stuck in ON when I deposit and
      > > examine a memory position). It's kind of fun to read the manual
      and
      > > play with this toy. Reminds me my early computer day with the PET
      > > Commodore and the Apple II. Documentation was included with lots
      of
      > > notes and schematics.
      > > I shot some pictures and posted them in the Photos section here.
      > >
      > > Enjoy and let me know waht you think of this baby,
      > >
      > > Jerome
    • Larry T.
      ... Jerome In my experience, the most likely causes of this kind of behavior are: 1) a bad memory chip 2) a bad buffer chip The only way to tell for sure is to
      Message 2 of 6 , Mar 1 8:15 AM
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        --- In altaircomputerclub@yahoogroups.com, "caljer" <caljer@y...>
        wrote:
        > Thx Steve. Exactly, window dressing!
        > I try to run the small addition program from the manual, but as I
        > said in my first post, whatever I deposit in a memory location has
        > bit D4 ON. (i.e. if I Deposit 00 000 000, I get 00 010 000 when I
        > Examine) So I have to check the wiring. I already cleaned the edge
        > connectors. The wiring is a little more involved...
        > Any other idea for this kind of behavior?

        Jerome

        In my experience, the most likely causes of this kind of behavior are:
        1) a bad memory chip
        2) a bad buffer chip
        The only way to tell for sure is to know the layout of the memory
        board. If there is more then one bank of ram chips and you know the
        size of the chips, pick an address that would be in a different bank
        of ram chips and see if the same bit is still 'stuck' after you
        deposit data. If there are more then two banks of chips, try this
        with each seperate bank. If it is a bad ram, only bad banks will
        show the problem, and if more then one bank is bad, the may well have
        the problem with a different bit. Be sure to test will all 0's AND
        all 1's! You might have problems such that you will always get a 0 no
        matter what data you poke! If you have mulitple memory boards, be
        sure to try all of the boards. If is is a buffer chip, all memory on
        the same board will have the problem. If all boards have the problem,
        then it is likely a buffer on the cpu board (I don't remember the
        Altair from panel having buffers for the data lines, but if so the
        problem may be there).

        Larry
      • Erik Klein
        Which store in Mountain View was it? I work off of Castro and would be curious if I d ever passed it and missed the old box. I ve seen similar memory issues
        Message 3 of 6 , Mar 1 9:04 AM
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          Which store in Mountain View was it? I work off of Castro and would be curious if I'd ever passed it and missed the old box.

          I've seen similar memory issues on my machines before. One possible issue could be a simple short in the bus. If one of the memory lines is shorted to another tied high or low then you might see a "stuck bit' situation.

          BTW, only some of the messages in this thread are making it to my inbox for some reason. I never did see your original post. . .

          Erik Klein
          www.vintage-computer.com
          www.vintage-computer.com/vcforum
          The Vintage Computer Forum


          caljer <caljer@...> wrote:
          Thx Steve. Exactly, window dressing!
          I try to run the small addition program from the manual, but as I
          said in my first post, whatever I deposit in a memory location has
          bit D4 ON. (i.e. if I Deposit 00 000 000, I get 00 010 000 when I
          Examine) So I have to check the wiring. I already cleaned the edge
          connectors. The wiring is a little more involved...
          Any other idea for this kind of behavior?

          I posted a higher def pic of the wire wrap board. The board has an
          UART TMS 6011 and two 555. I believe that it was wired as a dual
          function tape recorder interface and serial interface. But it's a
          guess based on connectors as well as schematics in the binder.


          Jerome


          --- In altaircomputerclub@yahoogroups.com, "Steve" <alltare@y...>
          wrote:
          > Thanks for posting the pictures. Your computer looks pretty
          clean.
          > Was the music store using it for anything other than a blinky-light
          > window dressing? Have you been able to run any programs on it
          yet?
          > What's the function of the blue wire wrap board in the pictures
          > labeled "MyAltair8800_10" and "MyAltair8800_11"?
          >
          > Steve
          > ==========================
          >
          > --- In altaircomputerclub@yahoogroups.com, "caljer" <caljer@y...>
          > wrote:
          > > Hello,
          > >
          > > I'm the proud owner of a MITS Altair 8800 serial# 222027K
          acquired
          > > sometime in 2003. I got it from a music store in Mountain View,
          CA.
          > > The computer was on display in the store window among various
          music
          > > intruments and with its LEDs blinking. I had to look several
          times
          > to
          > > make sure it was not some kind of fake computer. Kind of a chock,
          > > being a member of the Computer History Museum in Mountain View.
          > > <http://www.computerhistory.com>. I can now brag about it ;-)
          > >
          > > Anyway I have it now and it was sitting in my garage until today.
          I
          > > tested it (looks like one bit is stuck in ON when I deposit and
          > > examine a memory position). It's kind of fun to read the manual
          and
          > > play with this toy. Reminds me my early computer day with the PET
          > > Commodore and the Apple II. Documentation was included with lots
          of
          > > notes and schematics.
          > > I shot some pictures and posted them in the Photos section here.
          > >
          > > Enjoy and let me know waht you think of this baby,
          > >
          > > Jerome



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        • Steve
          Jerome, Your guess about it being a tape interface makes sense to me. One of the quirks of Yahoo is that only the person who posted a photo and the group
          Message 4 of 6 , Mar 1 10:38 AM
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            Jerome,

            Your guess about it being a tape interface makes sense to me.

            One of the quirks of Yahoo is that only the person who posted a photo
            and the group moderator are able to see the full size image.
            Everyone else has to live with a so-called "screen size" image that's
            usually only about 400 pixels wide. You can get around this by
            posting your image in the FILES folder rather than the PHOTOS
            folder. I've created a folder in FILES called JEROME, and I've put
            the full size image there.

            Besides doing the checks that Larry discussed, take the time to read
            through the message archives about other memory problems. You might
            find something useful. Also, check the white wires that run from the
            first mother board to the front panel. It's common to have one or
            more of them break off where they're soldered. Your computer was
            built a little differently than most. Usually, the first mother
            board was installed fully to the right side (as viewed from the
            front) of the computer. The 2nd, 3rd, and 4th mothers would then be
            added to the left of the 1st one. Your builder started in the
            middle. There's nothing wrong with that, but it does leave the white
            wires a little more vulnerable and messy than would otherwise be the
            case. Look at pictures of other 8800s and you'll see what I mean.

            You probably already know this, but let me give this warning anyway.
            When you're troubleshooting, NEVER pull a board out of the buss with
            the computer powered up. You'll most likely cause catastrophic
            damage. This has been discussed in the archives too.

            Steve
            ========================

            --- In altaircomputerclub@yahoogroups.com, "caljer" <caljer@y...>
            wrote:
            > Thx Steve. Exactly, window dressing!
            > I try to run the small addition program from the manual, but as I
            > said in my first post, whatever I deposit in a memory location has
            > bit D4 ON. (i.e. if I Deposit 00 000 000, I get 00 010 000 when I
            > Examine) So I have to check the wiring. I already cleaned the edge
            > connectors. The wiring is a little more involved...
            > Any other idea for this kind of behavior?
            >
            > I posted a higher def pic of the wire wrap board. The board has an
            > UART TMS 6011 and two 555. I believe that it was wired as a dual
            > function tape recorder interface and serial interface. But it's a
            > guess based on connectors as well as schematics in the binder.
            >
            >
            > Jerome
            >
            >
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